This is basically as originally posted uk.d-i-y on 13/06/1996, with
spelling corrections, and incorporating comments from the original
thread. See thread .
The original subject (complete with spelling error) was "Capilliary
fittings - how to solder successfully (LONG)"

This time the post is prompted by David W.E. Roberts who wrote on Fri, 1
Aug 2003 12:38:47 +0100 re "I LOVE Speedfit!" in message


Just thought I would re-iterate my love for Speedfit.

I can't solder to save my life, despite years of trying.
I have made many successful soldered joints.
However I have made at least the same number of unsuccessful ones, and they
are generally a b*ggger to fix once the water has been turned on and off
again.

I was using compression joints prior to discovering Speedfit.

I have just fitted a few compression joints in an area where I wanted to use
copper because it is stronger than plastic and I wanted it to be self
supporting.

Capillary Fittings - How to Solder them Successfully (Version 2)
----------------------------------------------------------------

Capillary Fittings are used for joining copper pipes with solder. There
are two basic types, with and without a pre-formed solder ring inside
them. Those with the solder ring are usually referred to as Yorkshire,
after the original manufacturer. Those without it are called end-feed,
because you have to supply the solder by feeding it in between the end
of the fitting and the pipe.

The following question - typical of those frequently asked - inspired
this description. Thanks to Peter Neville for the original question, and
to useful contributions at the time from Matthew Marks, John Laird, Jon
Rouse, Andrew Willoughby, Karel Hladky, Andy the Pugh, Wookey, Ed
Sirett, Simon Jenkins, and John Stumbles. This topic has been revisited
many times since, and a Google search will surely elicit additional
hints.

(Peter Neville) wrote:
I've just, unsuccessfully, tried to use a capillary fitting on a
15mm pipe. Total failure this time - I heated and heated and no
solder appeared.

These things don't need THAT much heat.

The fitting MUST be bone dry and so must the inside of the tube for AT
LEAST 12" from the joint. If there is ANY water lying in the pipe, or
dripping from above, you WILL NOT be able to solder it. Get rid of the
water, use a compression joint, or try that brilliant idea with the
bread. If there is no water flow you can dry out this 12" length with
the flame until steam stops appearing.

You MUST remove all traces of copper oxide from the mating surfaces with
wire-wool. Yes wire wool. Emery paper will NOT work, it reacts with the
copper in some way, neither will a file. Well, that's my experience -
others tell me that wet-and-dry paper works fine. Others say Scotchbrite
works. You can SOMETIMES get away without wire-wooling the INSIDE of the
fitting but its not worth omitting it because of the hassle of reworking
when it fails :-(. My little finger is just small enough to go into a
15mm capillary with a bit of wire-wool wrapped round it. Just one 360
degree wipe does the trick.

Some people swear by the use of acid fluxes which are said to avoid the
need for this thorough cleaning. I have not tried them myself.

Having cleaned BOTH parts you must lightly smear BOTH with flux. As
well as letting the solder flow this helps transfer heat between the
parts.

Do NOT OVERHEAT. If the solder ring does not appear before the flame
goes green something has gone wrong. Further heat will just distort the
parts and can prevent you getting them apart without wrecking something.

You are not supposed to need to add any extra solder but I most always
use extra solder to 'help' the solder ring to flow nicely. I use wire
solder from a reel, not the stuff in a solid bar.

WIPE off any external flux while still hot. This is easy to do but
plumbers never seem to bother. It eventually makes a green mess if you
leave it.

INSPECT the finished joint when cool to be sure the solder flowed all
round - otherwise you might have a leak. Visual inspection is final the
secret of good joints. If you cannot see a thin silver ring of solder
all around the jointed edge, there is something wrong.

If you want to solder the fitting to only one pipe leaving the other
connections till later, you MUST put a short length of UNCLEANED and
UNFLUXED tube in the other outlet(s) and make sure you use just enough
heat to flow the solder, and keep the heat away from the other ends. A
damp rag wrapped around the dummy stub will keep it cool if necessary
The idea is to be SURE the solder ring does not melt on that end. When
it's cool you can remove the dummy and the inner solder ring should be
intact.

Other tips:-

Make sure the pipe is cut square. Don't use a hacksaw, invest a fiver in
a pipe cutter tools which will make a square cut and with less effort.

Solder tends to run towards the heat, even uphill (a bit). So when you
solder a vertical tube coming upwards out of a fitting, get the pipe hot
before playing the flame on the fitting.

Always keep the heat even, i.e. move the flame all around the joint (or
at least heat a bit one side then the other).

Use a metal sheet to protect nearby materials, or an asbestos gauze
sheet obtainable from plumbers merchants for this purpose. Aluminium
cooking foil, wet rags or wet tissues have been used, too.

Be VERY careful when aiming the flame downwards between floorboards etc.
Dry wood ignites easily.

Use gloves to handle hot parts (ouch).

Cleaning surplus solder from parts: Heat until the solder melts, tap the
part on the bench edge to jolt the molten solder out, then WIPE the
surplus off with a DRY cloth. For cleaning off internal parts, attach
cloth to a wire and pull it through the component after heating to melt
solder.

Think about future modifications or repair to the system. You WILL NOT
be able to unsolder the joint if it is in a leg of pipe from which the
water cannot be drained. Consider using a compression joint, or a drain
cock, at a strategic place to allow dead legs to be drained. Otherwise
you have to cut the pipe.

Don't reuse old central heating tube on drinking water circuits - it
tastes foul.

Do make a practice assembly of all parts before soldering to be sure
lengths and bends are correct - much easier than unsoldering and
starting over!

Andrew Willoughby wrote:

I gave up using Yorkshires (solder ring) years ago. Endex are much cheaper and
you are more in control, you add the solder as and when you want to, far easier
when you get used to them. As for compressions! They _are_ hard work.

Andrew, I do agree, and all I said above also applies to end-feed
fittings (which have no pre-applied solder ring inside). You just need
to be even more rigorous to follow the advice, plus thoroughly wire-wool
the inside of the fitting, and of course feed in solder wire which has
been dipped in the flux tin.

More tips:

Practice with Yorkshires till you have the knack then try end-feeds. As
Andrew says, they are much cheaper. Use Yorkshire for that awkward
situation where the end-fed solder would have to go seriously uphill,
e.g. the fitting at the top of a vertical pipe.

A good joint has a convex meniscus ring of solder visible all around the
joint. If you don't see it, re-read the advice and start again.

--
Phil Addison
The uk.d-i-y FAQ is at http://www.diyfaq.org.uk/
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